package com.zekdot.registerclient.util;

import io.jsonwebtoken.*;
import org.bouncycastle.util.encoders.Base64;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SignatureException;
import java.util.Date;
import java.util.Map;

/**
 * Create by zekdot on 20-3-17.
 */
public class JwtUtil {
    public static String JWT_SECERT = "shudaixiong";
    public static String JWT_NOT_ADMIN = "{\"code\":1019,\"message\":\"您没有该权限\"}";
    public static String JWT_NO_INFO = "{\"code\":1020,\"message\":\"没有鉴权信息\"}";
    public static String JWT_FAIL = "{\"code\":1021,\"message\":\"无效的token\"}";
    public static String JWT_EXPIRE = "{\"code\":1022,\"message\":\"token过期，请重新登录\"}";
    public static String JWT_WRONG_IDENT = "{\"code\":1023,\"message\":\"token与身份不符\"}";

    /**
     * 生成密钥
     * @return
     */
    private static SecretKey generalKey() {
        byte[] encodedKey = Base64.decode(JWT_SECERT);
        SecretKey key = new SecretKeySpec(encodedKey, 0, encodedKey.length, "AES");
        return key;
    }
    /**
     * 签发JWT
     * @param id
     * @param subject 可以是JSON数据 尽可能少
     * @param ttlMillis
     * @return  String
     *
     */
    public static String createJWT(String id, String subject, Map<String,Object> claimMap, long ttlMillis) {
        SignatureAlgorithm signatureAlgorithm = SignatureAlgorithm.HS256;
        long nowMillis = System.currentTimeMillis();
        Date now = new Date(nowMillis);
        SecretKey secretKey = generalKey();
        JwtBuilder builder = Jwts.builder()
                .setId(id)
                .setSubject(subject)   // 主题
                .setIssuer("zekdot")     // 签发者
                .setIssuedAt(now)      // 签发时间
                .signWith(signatureAlgorithm, secretKey); // 签名算法以及密匙
        for(String key:claimMap.keySet()){
            builder.claim(key,claimMap.get(key));
        }
        if (ttlMillis >= 0) {
            long expMillis = nowMillis + ttlMillis;
            Date expDate = new Date(expMillis);
            builder.setExpiration(expDate); // 过期时间
        }
        return builder.compact();
    }
    /**
     * 验证JWT
     * @param jwtStr
     * @return
     */
    public static CheckResult validateJWT(String jwtStr) {
        CheckResult checkResult = new CheckResult();
        Claims claims = null;
        try {
            claims = parseJWT(jwtStr);
            checkResult.setSuccess(true);
            checkResult.setClaims(claims);
        } catch (ExpiredJwtException e) {
            checkResult.setErrCode(checkResult.JWT_ERRCODE_EXPIRE);
            checkResult.setSuccess(false);
        } catch (SignatureException e) {
            checkResult.setErrCode(checkResult.JWT_ERRCODE_FAIL);
            checkResult.setSuccess(false);
        } catch (Exception e) {
            checkResult.setErrCode(checkResult.JWT_ERRCODE_FAIL);
            checkResult.setSuccess(false);
        }
        return checkResult;
    }



    /**
     *
     * 解析JWT字符串
     * @param jwt
     * @return
     * @throws Exception
     */
    private static Claims parseJWT(String jwt) throws Exception {
        SecretKey secretKey = generalKey();
        return Jwts.parser()
                .setSigningKey(secretKey)
                .parseClaimsJws(jwt)
                .getBody();
    }
}
